We are studying the smooth pursuit eye movement system by means of physiological and psychophysical techniques. To date, we have shown involvement of both perception of target motion and target position in controlling smooth pursuit eye movements. (This is in addition to the physical motion of the target image on the retina.) In the next part of our work, we will: Attempt to define more quantitatively the relationship between perception of target motion and pursuit eye movements; attempt to define more quantitatively the response of the pursuit eye movement system to target position; and begin to investigate the predictive capacities of the smooth pursuit eye movement system, and the role of prediction in normal oculomotor behavior.